resend.com

AI agents cannot complete MCP server initialization handshake and lack clear error response documentation for email delivery API calls.

28 pass · 4 warn · 2 fail · 7 n/a

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Discovery

21.2/22.2

Accessibility

32.1/33.3

Usability

30.2/44.4

Payments

n/a

Discovery 21.2/22.2

API reference linked from the homepagedetailsWARN
no link to an API reference in the homepage HTML
Fix: If you have an API, link its reference from the homepage. If you don't, this check is safe to ignore.
Canonical URL declareddetailsPASS
https://resend.com
Documentation linked from the homepagedetailsPASS
5 docs link(s), e.g. https://resend.com/docs

Badge

Shows the current scan score and grade for this domain, straight from the latest static pre-check.

[![agent ready](https://www.vorza.dev/api/badge/resend.com)](https://www.vorza.dev/score/resend.com)

<a href="https://www.vorza.dev/score/resend.com"><img src="https://www.vorza.dev/api/badge/resend.com" alt="agent readiness score" /></a>

Homepage has a meta description

details

PASS

106 characters

Homepage has a descriptive titledetailsPASS

'Resend · Email for developers' (29 chars)

Listed in the official MCP registrydetailsPASS

listed as (unnamed)

Open Graph tags presentdetailsPASS

og:title and og:description present

robots.txt allows agent crawlersdetailsPASS

all 6 agent crawlers may fetch /

robots.txt existsdetailsPASS

HTTP 200, 143 bytes

robots.txt points at the sitemapdetailsPASS

robots.txt has a Sitemap: line

sitemap.xml exists and parsesdetailsPASS

11 URL(s) listed

Accessibility 32.1/33.3

Content-to-markup ratio is reasonabledetailsWARN
ratio 0.0336 — 14314 readable chars in 425552 bytes of HTML
Fix: Most of what you serve is markup and inline script rather than content. Reduce inline payloads or server-render more text so the signal-to-noise ratio favours readers.
Docs are readable without JavaScriptdetailsPASS
1747 characters of text at /docs
Homepage responds to an agent requestdetailsPASS
HTTP 200 for / (agent UA)
Served over HTTPSdetailsPASS
https://resend.com/
Structured data (JSON-LD) on the homepagedetailsPASS
1 valid block(s)
llms-full.txt is publisheddetailsPASS
HTTP 200, 8036 bytes
llms.txt is publisheddetailsPASS
HTTP 200, 5657 bytes
Links in llms.txt resolvedetailsPASS
5 sampled link(s) all resolve
llms.txt is structured markdowndetailsPASS
has headings and markdown links
Serves markdown when asked for itdetailsPASS
Accept: text/markdown → text/markdown; charset=utf-8
Same response for agents and browsersdetailsPASS
both User-Agents got HTTP 200
Homepage has readable text without JavaScriptdetailsPASS
14314 characters of text in the served HTML
No long redirect chain on the homepagedetailsPASS
0 redirect(s)

Usability 30.2/44.4

MCP server completes the initialize handshakedetailsFAIL
handshake failed: response was not a JSON-RPC message
Fix: Make https://resend.com/mcp answer a streamable-HTTP `initialize` request. Check that POST is allowed, that `Accept: application/json, text/event-stream` is honoured, and that the response is a JSON-RPC envelope.
OpenAPI documents error responsesdetailsFAIL
no 4xx/5xx responses documented on any operation
Fix: Document your error responses with codes and schemas. Undocumented failures are where agent integrations silently break.
agents.md is publisheddetailsWARN
/agents.md not served (HTTP 404)
Fix: Publish /agents.md: what an agent may do here, which endpoints matter, auth requirements, and rate limits. It is the agent-facing counterpart to a README.
Errors are machine-readabledetailsWARN
404 returns HTML, not a machine-readable body
Fix: Content-negotiate your errors: return a JSON body with a stable `code` (and a `next_action` where recovery exists) to clients that ask for JSON.
A documentation endpoint respondsdetailsPASS
/docs → HTTP 200
OpenAPI declares its auth schemedetailsPASS
1 scheme(s): bearerAuth
OpenAPI operations are describeddetailsPASS
83/83 operations described (100%)
OpenAPI document publisheddetailsPASS
HTTP 200, 200008 bytes of JSON
OpenAPI document is structurally validdetailsPASS
OpenAPI 3.0.3, 47 path(s)
.well-known/mcp.json advertises an MCP serverdetailsPASS
HTTP 200, valid JSON
The /api root behaves predictablydetailsN/A
/api → HTTP 404 (no API at the conventional root)
MCP tool parameters are typed and describeddetailsN/A
no listed MCP tools to inspect
Every MCP tool has a descriptiondetailsN/A
no listed MCP tools to inspect
MCP server lists toolsdetailsN/A
handshake did not complete, so tools/list was not reached

Payments not applicable — excluded from the score

Serves a 402 payment challengedetailsN/A
no agent-payment rail published — not applicable. This layer is excluded from the score rather than counted against the site.
Declares AP2 / ACP supportdetailsN/A
no agent-payment rail published — not applicable. This layer is excluded from the score rather than counted against the site.
Publishes x402 payment metadatadetailsN/A
no agent-payment rail published — not applicable. This layer is excluded from the score rather than counted against the site.